Steels and castings are conventionally cut using cutting tools made of materials such as cemented carbides. The inserts of these cutting tools are exposed to elevated temperatures, i.e., 800° C. or higher, during cutting. The heat generated during cutting causes problems such as plastic deformation and increased flank wear of the cutting tools.
To achieve improved cutting performance at elevated temperatures, surface-coated cutting tools including various coatings formed on substrates made of materials such as cemented carbides have been proposed. As one example, PTL 1 discloses a coated tool including a boron-containing coating formed over an aluminum oxide coating. As another example, PTL 2 discloses a cutting tool including a titanium diboride layer formed on a substrate material.